CEL Codes 34 + 31

[JamesM007]

The dealer says my 94 limited is sending out codes 34 and 31. Their reccomendation (taken from the repair order) is:


"EEC EFI diagnosis pin point tested and monitor tested needs a DPFE sensor and EGR valve also needs a EVR selenoid."


Should I replace all three or just start with the DPFE, EGR, then EVR. Also, can anyone tell me what these codes are or give me a link to decipher them?

Thank you.

007

 

[Glacier991]

James..

To begin with here is a good link for codes.

http://autorepair.about.com/library/ts/obd-i/bl-dtcs-main.htm

I am surprised your 94 is sending out 2 digit codes, I thought all the 94's were 3 digit. Anyway code 31 is

31 EVP circuit below minimum voltage, and 34 is
34 EVP voltage above closed limit

The EVP essentially measures the position of the EGR valve so the computer knows what it's doing. It's possible the EVP is fine and the EGR is bad, it's also possible the EVP is bad and the EGR is fine, or they both may be bad. If your vehicle has a DPFE sensor it too may be bad (and in fact it is more often the culprit). If you have a vacuum tester you can test these components, but if you are simply going to replace them, I'd do the DPFE first, before the EGR. If you want more detail on how to test them, let me know.

Happy Exploring

Chris